This invention concerns a process for making aminecarbotrithioates by reaction between a thiosulfonate and an aminecarbodithioate salt, advantageously an alkali metal or ammonium salt. The reaction is carried out advantageously in the presence of one or more organic liquids in which either or both of the reactants is dissolved or suspended, and at a temperature ranging between about 20.degree. and about 150.degree.C., if desired under an inert atmosphere, e.g., nitrogen. The invention also concerns certain novel aminecarbotrithioates. The aminecarbotrithioates have biological activity, particularly in controlling microorganisms and other pests.